The present invention relates in general, to electronics, and more particularly though not exclusively, to switched mode power sources (SMPS), to buck converters, to semiconductors, structures thereof, and methods of forming semiconductor devices.
FIG. 1 illustrates a buck converter 100 that uses a shield gate switch 101 as a control (ctrl) switch with nodes (e.g., 181, 182, 183). The shield gate switch 101, includes a source electrode S/B 130, a plate 155 and associated plate electrode P 150, a gate 165 and associated gate electrode G 160. The drain D 140 is connected to the gate G 160 via several capacitors (C1 and C2). The gate G 160 is connected to plate P 150 via the capacitor C1. The plate P 150 is connected to source S/B 130. The control switch 101 is connected to the output or switching node (Vsw) via node 182. Each node is associated with a signal, with ctrl switch node 181 associated with a control signal 161 Vgctrl, switching node 182 associated with a switching signal 162 Vsw, and synchronization (sync) node 183 associated with a synchronization signal 163 Vgsync.
FIG. 2 illustrates the ringing of the voltages (Vgctrl 161, Vsw 162, and Vgsync 163) that can occur in related art buck converter systems. In DC/DC buck converters with shield-gate switches, when the ctrl switch 101 is turned on, voltage ringing can occur. For example, voltage (Vgctrl 161) ringing at the ctrl switch node 181 can be amplified when connecting the plate electrode 150 to the source 130. The ringing of the voltage (Vsw 162) at the switching node 182 can be transmitted to the driver, thus complicating the circuit control for the buck converter 100, compromising its reliability. Moreover, the voltage capability of the ctrl 101 and sync 102 power switches is overrated to avoid the avalanche phenomenon, facilitating conduction losses in the buck converter 100.
Accordingly, a configuration is needed which damps voltage ringing without reducing the efficiency of the system where the configuration does not impart additional process complexity or extra manufacturing cost.